Five Newly Container Vessels Design

1. Marlin-Class Container Ship Design

The Marlin-class vessels are the world's first container ships powered by liquefied natural gas (LNG).The Marlin-class ships are designed to burn either fuel oil, or gas, derived from LNG, thereby significantly decreasing gaseous emissions and increasing fuel efficiency, when compared with conventionally powered ships. The clean-burning LNG fuel of the new Marlin-class vessels provide exceptional environmental benefits, such as considerable reductions in particulate matter (PM) by 99%, sulphur oxide (SOx) emissions by 98%, carbon dioxide (CO2) emissions by 71% and nitrous oxide (NOx) emissions by 91%.

Figure 1. container ships powered by liquefied natural gas (LNG)

2. Triple-E Class Container Ships Design

The Triple-E class is an improved and modified version of Emma Maersk, one of the largest active vessels in the world. Emma Maersk can carry 15,500TEU. Triple-E (EEE) stands for economy of scale, energy-efficient and environmentally improved vessel. The vessels operate in the Europe-Asia route, with stoppages at Shanghai, Ning-bo, Xiamen, Yantian and Hong Kong ports.
a.) U-Shape Hull

 Figure 2. U-Shape Hull

The improved vessel has a U-shaped hull so more containers can be accommodated at lower levels. The 165,000t vessel has a length of 400m. The beam is 59m and draught is 15.5m. The height above baseline is 73m, one meter higher than the highest ship Allure of the Seas. The new ships are designed to cruise at a top speed of 23k. The navigation bridge and accommodation areas were relocated to five bays forward. The engine room and chimney were moved six bays back. These modifications create space for 1,000 extra containers. In all, the new vessels carry 2,500 more containers compared to Emma Mærsk.
b.) Twin Skeg Propulsion System

 Figure 3. Twin Skeg Propulsion System

The Triple-E class vessel has a twin skeg propulsion system, with two slow running ultra-long stroke engines. Each engine drives a separate propeller. Each engine produces 43,000hp and weighs 910t. Each consumes 168g bunker oil per kWH produced. Each of the two propellers has a diameter of 9.8m and four blades. The smaller the number of blades, the lower the resistance; while the larger diameter propellers produce more pushing power. The two engines and two propellers combination generate further savings of 4% energy when compared to a combination of one engine and one propeller.

3. Skysail

Figure 4. Sky sails

‘Skysails’ is that genre of engineering science that uses extensive utilization of wind energy to move a vessel in the sea water. The specific towing kite is made in such a way that it can be raised to its proper elevation and then brought back with the help of a ‘telescopic mast’ that enables the towing kite to be raised properly and effectively. skysails allow a naval vessel to generate 25 times more thrust per square meter than conventional sails, and in good wind conditions can deliver the quivalent of 2,000 kW of propulsion.

4. Double Hull

Double hull is a construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard. The double layer construction helps in reducing the risks of marine pollution during collision, grounding, and any other form of ship’s hull damage.
The International Maritime Organisation (IMO) introduced the regulation 13 F of Annex 1 of MARPOL, which effectively mandated double hulls for new built oil tankers of 5000 dead weight tonnage and above. After the sinking of Erika off the coast of France in December 1999, IMO proposed accelerating phase out of single hull ships. And double hull also can aplly on container ships.
According to a research, stresses in the structure of double hull ships are much higher than that in single hull ships. Thus double hull ships are more susceptible to minor structural failures as compared to the single hull tankers. This can also be a matter of concern during accidents which cause oil spill as a result of structural failure.

5. Cold Ironing

 Figure 5. Cold Ironing

Cold Ironing which is also known as Alternative Marine Power (AMP), involves plugging a ship in port directly into shore based power. Shutting down main engines while in port continues as a majority practice. However, auxiliary diesel generators that power cargo handling equipment and other ship's services (such as: emergency equipment, refrigeration, cooling, heating, lighting and other equipment to receive continuous electrical power while the ship loads or unloads its cargo) while in port are the primary source of air emissions from ships in ports today, because the auxiliaries run on heavy fuel oil or bunkers.
Cold ironing mitigates harmful emissions from diesel engines by connecting a ship's load to a more environmentally friendly, shore-based source of electrical power. An alternative is to run auxiliary diesels either on gas (LNG or LPG) or extra low sulphur distillate fuels. Typically, a vessel runs auxillary engines while in port to provide power. Cold ironing allows the vessel to shut down all its engines and has the potential to significantly reduce fuel consumption and port pollution levels.